645 research outputs found
New Multiphase CP and DP 1000 MPa strength level grades for improved performance after hot forming
Pure martensitic steels have after hot forming limited performance in terms of rest ductility which limits the application in crash relevant parts. New steel grades were designed in the EU project HOTFORM including the corresponding process routes. These steel grades have ferritic-martensitic dual phase (DP) and martensitic-bainitic complex phase (CP) microstructures after hot forming process. The laboratory tests show an improved formability after hot forming. The basic concepts of the new alloys are explained. Furthermore, for validation of upscaling purposes a semi-industrial test is carried out and the results are discussed. The main application is for vehicle safety. This is evaluated by comparing the crash performance of these hot formed grades with cold rolled DP1000 and CP1000 for crash cans in a drop tower test.The research leading to these results was carried out in the framework of HOTFORM project with a financial grant of the Research Programme RFCS (Research Funds for Coal and Steel) under grant agreement (RFSR-CT-2015-00017)
Evaluation of colorimetric changes in the Itaquera granite of the Ramos de Azevedo Monument, São Paulo, Brazil
10 páginas, 6 figurasItaquera Granite, as a building stone material, was widely used in the early 20th century for the construction of buildings and monuments in the centre of the city of São Paulo, Brazil. The color variation of the Itaquera Granite of the Ramos de Azevedo Monument was monitored for two years and these data were compared with those obtained for fresh stone originated from a historic quarry. The oxidation of iron-rich minerals present in this granite, coupled with pollution (high levels of O3), biological colonization, leaching of bronze, and the dissolution and reprecipitation of mortar, causes colorimetric changes in the stone. Measurements were also performed on zones of the monument with pathologies. Two statistical Canonical Biplot analyses were made on the data of chromatic coordinates monitored (L*, a*, b*, C* and H*): orientation/year and orientation/pathologies. The results obtained for the chromatic variation in the monument are primarily related to yellowing caused by deposition of atmospheric pollutants and weathering of iron-rich minerals.FAPESP (Foundation for Research Support of the State of São Paulo) for granting the
master’s scholarship (proj. no. 2011/03728-0) and research grant (proj. no. 2009/02519-8)Peer reviewe
Optimization of a Slurry Dispersion Method for Minerals and Trace Elements Analysis in Infant Formulae by ICP OES and FAAS
Infant formula developed by manufacturers requires a rigorous control of composition,
particularly those elements added routinely in an attempt to mimic the mineral
composition of human milk. A total of 97 different types of powdered infant formulae
(preterm, adapted starter, adapted follow-up, toddler, specialised and soy based
formulae) commercially available in Spain were studied. It is noteworthy great
differences in mineral (Ca, P, Mg) and trace element (Zn, Fe, Cu, Mn) contents found
between analysed and listed in label information. The development of a fast, simple and
direct slurry method for the determination of these essential micronutrients in infant
formula by inductively coupled plasma optical emission spectrometry (ICP OES) and
flame atomic absorption spectrometry (FAAS) was performed in order to help in quality
control tasks. Infant formula samples were solubilised using different amounts of
several different solvents. An addition of 250 L of a solution 10 %
tetramethylammonium hydroxide and 25 % ammonium hydroxide were required for the
accurate quantification of Ca and P, Mg, Zn, Fe, Cu and Mn, respectively. The standard
reference material 1549 non-fat milk powder was solubilised to compare the validity of
assayed methodology following slurry nebulisation and traditional microwave-assisted
acid digestion method. Good agreement of the analytical results by both ICP OES and
FAAS, with the certified values was obtained. Method performance parameters
(accuracy, precision and methodological detection limits) were determined for studied
elements to check the quality and usefulness of the optimised slurry method. The
analytical procedure was applied successfully to the analysis of a representative group
of infant formulae. Levels of analysed elements were graphically represented, showing
an acceptable comparability between slurry and acid-mineralisation method set by linear
correlation coefficients and slopes close to the unit. The described simple and slurry
method is appropriate, as an attractive alternative, for routine control analysis of added
essential elements in infant formulae regardless of predominant protein type used in
manufacture
Number operator-annihilation operator uncertainty as an alternative of the number-phase uncertainty relation
We consider a number operator-annihilation operator uncertainty as a well
behaved alternative to the number-phase uncertainty relation, and examine its
properties. We find a formulation in which the bound on the product of
uncertainties depends on the expectation value of the particle number. Thus,
while the bound is not a constant, it is a quantity that can easily be
controlled in many systems. The uncertainty relation is approximately saturated
by number-phase intelligent states. This allows us to define amplitude
squeezing, connecting coherent states to Fock states, without a reference to a
phase operator. We propose several setups for an experimental verification.Comment: 8 pages including 3 figures, revtex4; v2: typos corrected,
presentation improved; v3: presentation considerably extended; v4: published
versio
Chromium content in different kinds of spanish infant formuale and estimation of dietary intake by infants fed on reconstituted powder formulae
The essentiality of chromium in humans is well documented. Trivalent chromium, main
chemistry form found in foods, is essential for maintaining normal glucose metabolism.
Because of analytical difficulties, several literature reports of chromium content of foods,
especially for the lower levels, show large variability and they should be interpreted with
caution for a valid interpretation of reliable results. A Zeeman background correction
transversely-heated graphite furnace atomic absorption spectrometry was used to
determine the chromium content of 104 different infant formulae (cow’s milk and soy
protein based) marked in Spain following an acid attack sample preparation procedure in a
closed, pressurized and microwave digestion unit.
Mean and range chromium values, regarding types and main protein-based infant formulae
are presented. Additionally, the influence of the type of container used, the impact of
industrial process from different manufacturers and the physical state (powder and liquid
formulae) on chromium levels is also discussed. In general, the infant formulae contain a
higher chromium concentration than that found in human milk (reference range: 0.20 –
8.18 g l-1), particularly in case of hypoallergenic (18.16 ± 7.89 g l-1), lactose-free (11.37
± 3.07 g l-1), preterm (11.48 ± 3.15 g l-1) and soya (10.43 ± 4.05 g l-1) formulae. The
maximum theoretical estimated intake of infant fed on studied formulae was lower than the
upper limit safety for trivalent chromium of 1 mg kg-1 (14 g Kg-1 b.w. day-1)
recommended by the experts of Council for Responsible Nutrition (CRN ULS, 2004),
amounting to about 10 %, 15-18 % and 26 % for standard (adapted and follow-up) and
toddler; soya, lactose-free and preterm; and hypoallergenic formulae, respectively.
Therefore, manufacturers are called for continued effort to routinely monitor chromium
levels, mainly for specialised and preterm formulae, and at the same time, might consider
the inclusion of labelling value for chromium at least in these complex formulations
Protaceratherium platyodon (Rhinocerotidae, Mammalia) del yacimiento Mioceno de Corcoles (Guadalajara, España)
This paper deals with the aceratherine remains fram the Lower Miocene of Córcoles (Guadalajara) classified as Protaceratherium platyodon. Their comparative study supports the synonymy between Protaceratherium and Plesiaceratherium and between «Plesiaceratherium» platyodon and «Plesiaceratherium» lumiarense.En este trabajo se estudian los restos de aceraterino del Mioceno Inferior de Córcoles, determinados como Protaceratherium platyodon. El estudio comparativo realizado confirma la sinonimia entre Protaceratherium y Plesiaceratherium, asà como entre «Plesiaceratherium» platyodon y «Plesiaceratherium» lumiarense
Chemometric analysis of minerals and trace elements in raw cow milk from the Community of Navarra
The concentrations of protein, fat, five minerals (Na, K, P, Ca and Mg) and nine trace elements (Fe, Zn, Cu, Mn, Se, Al, Cd, Cr and Pb) have been determined in 347 samples of raw cow milk from the community of Navarra, north Spain, using infrared analysis, atomic absorption spectrometry (flame and electrothermal atomisation) and inductively coupled plasma atomic emission spectroscopy. A preliminary chemometric study with the use of pattern recognition methods was carried out in order to characterise, classify and distinguish the different collected samples on the basis of their contents. Principal component analysis (PCA) has permitted the reduction of 16 variables to five principal components which interpret reasonably well the correlations of these studied variables. These variable associations may be attributed to intrinsic (lactogenesis) and other extrinsic factors, such as seasonal variation, animal feeding or geographical situation. Changes in these contents during different seasons were also assessed and consistently interpreted. Linear discriminant analysis (LDA) was used to explore cow milk samples, classifying according to season or geographical location, providing complementary information to PCA. This work shows that PCA and LDA are useful chemometric tools for the multivariate characterisation of raw cows’ milk
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